This invention relates generally to semiconductor devices, and more specifically, to apparatuses and methods for manufacturing semiconductor devices.
The demounting or debonding process for separating thinned semiconductor substrates from their support substrates is one of the main identified causes for semiconductor substrate breakage during the manufacturing of semiconductor devices. Semiconductor substrate breakage is very costly because the demounting step is performed near the end of the manufacturing process, after most of the manufacturing costs have already been incurred.
Currently, the majority of the semiconductor device manufacturing industry uses a single semiconductor substrate separation process for semiconductor substrate demounting. Using this method, a single semiconductor substrate is separated from its support substrate one at a time. This process typically involves: (1) placing the support substrate and the semiconductor substrate, or ceramic substrate, onto a heated surface to melt an adhesive or grip material such as a wax or a mixture of wax with photoresistor that connects the support substrate to the semiconductor substrate, and (2) manually demounting the semiconductor substrate from the support substrate after the adhesive is melted in order to separate the semiconductor substrate from the support substrate.
One of the problems with the existing method of the semiconductor substrate separation process is that high incidents of semiconductor substrate breakage occur due to human error during the manual performance of the demounting step. This occurs because the semiconductor substrates become fragile when they are physically thinned by a grinder or a lapper machine, or they are chemically thinned by a chemical such as acid, during the processing of the semiconductor substrates. Via holes are drilled on the support substrates, which are typically made of sapphire, to make the dissolving agent permeate the support substrate and dissolve the adhesive. This is also a very costly process. Further, the demounted semiconductor substrates float in the dissolving solution and are subject to a significant amount of turbulence created by ultrasonic vibrations utilized in the process. Due to this process, the semiconductor substrates become extremely fragile during the demounting process, making manual performance of the demounting step extremely prone to human error and resulting in semiconductor substrate breakage.
Another problem with the existing process used to separate the thinned compound semiconductor substrate, or a ceramic substrate, from its support substrate is lack of efficiency. The existing demounting process is not efficient because the semiconductor substrates need to be manually and carefully demounted from their support substrates one at a time.
Due to the problems with the existing method of demounting, there is a need for a non-manual method of demounting or separating semiconductor substrates from their support substrates simultaneously and efficiently without breaking or otherwise fracturing the semiconductor substrates.
This invention is directed to a method and apparatus for a non-manual method of demounting semiconductor substrates from their support substrates simultaneously and efficiently without damaging the semiconductor substrates.
A preferred version of the process of separating one or more semiconductor substrates from one or more support substrates having features of the present invention comprises the following steps. The first step comprises providing an apparatus having: (a) a top cassette having a plurality of vertical slots, and one or more small bars for stopping the support substrate from exiting the top cassette; and (b) a bottom cassette having a plurality of vertical slots. The next step comprises vertically inserting the semiconductor substrate into the slot of the top cassette while the semiconductor substrate is coupled to the support substrate, wherein the surfaces of each semiconductor substrate is positioned approximately parallel to a force of gravity during the inserting step. Then, the supporting step comprises supporting the support substrate above the small bars in the top cassette. Next, the introducing step comprises introducing the apparatus to a dissolving agent to separate the semiconductor substrate from the support substrate, wherein the first surface of each semiconductor substrate is positioned approximately parallel to the force of gravity during the introducing step, and wherein the force of gravity moves the semiconductor substrate from the top cassette towards the bottom cassette. The next step comprises removing the top cassette from the apparatus. This is followed by the exposing step that comprises exposing the apparatus to a cleaning agent to clean the semiconductor substrate. Next step comprises drying the semiconductor substrate after the cleaning step.
In another embodiment of the present invention, the providing step further comprises a basket in which the bottom cassette and the top cassette are placed.
In yet another embodiment of the present invention, the providing step further comprises providing the bottom cassette having a first wall, a second wall substantially parallel to the first wall and coupled to the first wall, a large bar embedded inside the first wall; and a large bar embedded inside the second wall, such that a distance between the two bars is shorter than a greatest surface length of the semiconductor substrate.
In yet still another embodiment of the present invention, the providing step further comprises providing the bottom cassette having a tapered end such that the semiconductor substrate is stopped from exiting the bottom cassette through the tapered end.
In another embodiment of the present invention, the providing step further comprises providing the support substrate that is optically transparent.
In still embodiment of the present invention, the providing step further comprises providing the support substrate having one or more via holes.
In another embodiment of the present invention, the inserting step further comprises preventing the small bars from contacting the semiconductor substrate.
In yet another embodiment of the present invention, the moving step further comprises moving the semiconductor substrate towards the bottom cassette without removing the semiconductor substrate from the apparatus.
In yet still another embodiment of the present invention, the introducing step further comprises exposing the semiconductor substrate to a chemical to release the semiconductor substrate from the support substrate.
In still another embodiment of the present invention, the introducing step further comprises heating the semiconductor substrate to release the semiconductor substrate from the support substrate.
In another embodiment of the present invention, the introducing step further comprises subjecting the apparatus to an ultrasonic treatment to release the semiconductor substrate from the support substrate.
A preferred version of the apparatus of separating one or more semiconductor substrates from one or more support substrates having features of the present invention comprises a top cassette having one or more small bars for stopping the support substrate inside the top cassette, and a bottom cassette for receiving the semiconductor substrate.
In another embodiment of the present invention, the bottom cassette has one or more large bars such that the semiconductor substrate remains inside the bottom cassette after being received.
In yet another embodiment of the present invention, the bottom cassette has one or more tapered ends such that the semiconductor substrate remains inside the bottom cassette after being received.
In yet still another embodiment of the present invention, the apparatus further comprises a basket in which the bottom cassette and the top cassette are placed.
In still another embodiment of the present invention, the apparatus further comprises the top cassette and the bottom cassette having a first wall, a second wall being substantially parallel to the first wall and coupled to the first wall, a plurality of tabs extending from each wall towards the other wall, wherein the plurality of tabs have approximately equal lengths and are substantially coplanar with each other.
In another embodiment of the present invention, the apparatus further comprises: (a) the top cassette having one or more top pins extending from a bottom surface of the first wall, and one or more top pin apertures on a bottom surface of the second wall; (b) the bottom cassette having one or more bottom pins extending from a top surface of the second wall, and one or more bottom pin apertures on a top surface of the first wall. The top pin on the top cassette is inserted into the bottom pin aperture on the bottom cassette. The bottom pin on the bottom cassette is inserted into the top pin aperture on the top cassette. The plurality of tabs on the top cassette is substantially aligned with the plurality of tabs on the bottom cassette. The top cassette and the bottom cassette are attached in vertical alignment.
In yet another embodiment of the present invention, the apparatus further comprises the bottom cassette having the first wall and the second wall made of metal coated with tetrafluoroethylene polymer fiber.
In yet still another embodiment of the present invention, the small bar is made of a material containing tetrafluoroethylene polymer fiber.
In still another embodiment of the present invention, a first small bar is embedded within an aperture on the first wall and a second small bar is embedded within an aperture on the second wall, such that a distance between the two small bars is shorter than a greatest surface length of the supporting substrate but longer than a greatest surface length of the semiconductor substrate.
Another preferred version of the apparatus of separating one or more semiconductor substrates from one or more support substrates having features of the present invention comprises a top cassette and a bottom cassette. Each cassette has a first wall, a second wall being substantially parallel to the first wall and coupled to the first wall, a first interior surface on the first wall facing towards the second wall, a second interior surface on the second wall facing towards the first wall. Each cassette also has a plurality of tabs extending from the first interior surface towards the second interior surface, where the tabs have approximately equal lengths and are substantially coplanar with each other. It also has a plurality of tabs extending from the second interior surface towards the first interior surface, where the tabs have approximately equal lengths and are substantially coplanar with each other. The top cassette has one or more small bars made of a material containing tetrafluoroethylene polymer fiber along the interior surface of at least one wall for stopping the support substrate inside the top cassette from dropping into the bottom cassette. The bottom cassette for receiving the semiconductor substrate has a stopping means to hold the semiconductor substrate within said bottom cassette after being received. The top cassette is capable of receiving the semiconductor substrate, and the support substrate is coupled to the semiconductor substrate in a manner whereby a first surface of the semiconductor substrate is positioned substantially parallel to a force of gravity. The top cassette is attached to the bottom cassette, such that the plurality of tabs on the top cassette is substantially aligned with the plurality of tabs on the bottom cassette, such that the top cassette and the bottom cassette are attached in vertical alignment.
In another embodiment of the present invention, the apparatus further comprises the top cassette further comprising one or more top pins extending from a bottom surface of the first wall, and one or more top pin apertures on a bottom surface of the second wall. The apparatus also has the bottom cassette further comprising one or more bottom pins extending from a top surface of the second wall, and one or more bottom pin apertures on a top surface of the first wall. The top pin on the top cassette is inserted into the bottom pin aperture on the bottom cassette and the bottom pin on the bottom cassette is inserted into the top pin aperture on the top cassette, such that the top cassette and the bottom cassette are attached in vertical alignment.